I am with Zork of The Fifth Element on this one: Honor is just an excuse butchers make up to cover their atrocities. The man slaughtered his own tribe, he razes an entire city instead of, you know, converting it's vast spaces or something (and with the Legion's track record I seriously doubt he politely asked the hundreds or even thousands dwelling in it to move out of the way), he pursues the Remnants with no regards for the life of his men (if he did, he would have given up after a few tries, spears and machetes are no good against Power Armor and a Vertibird, as it should be), and his ending more or less implies he just attack-moves his armies West destroying all in his path. Yes, a real gentlemen there, just what the Wasteland needs, more warlords causing untold destruction where there was once peace.
Really, defending the Legion is a bit of a stretch, but Lanius? He is the worst of the lot save maybe for Vulpes Inculta.
And about the NCR's ineptitude, they still are the only faction in the Fallout canon to actually get things done, if we forget that Capital Wasteland White Knight's Happy Go-Round business known otherwise as Lyon's Brotherhood. We see them protecting the population (Goodsprings, Primm and Novac fare the best under their rule, the others either ignore or crush them), develop the economy with their caravans, are willing to cooperate with the other major factions (the two other major powers require you to exterminate at least one), implement large-scale agricultural projects (far more important to the Wasteland that Ceasar's ''glory'' or House's casinos), not to mention holding off the cosplaying psychos on the other side of the Colorado. For all that talk about the NCR being inept they did a lot of things in the Mojave, they are certainly not perfect but this is Fallout, nobody is.